The present invention relates to a high-strength panel-type article and to a process for manufacturing the same.
Films and panel-type articles are two of the most important forms in which plastics are produced as semifinished products. While in film production monoaxial or biaxial drawing is used industrially to improve the mechanical properties, drawing is hardly used at all in panel manufacture. The chief reasons for this are the problems directly connected with the panel thickness, namely, on the one hand, of mechanically controlling in the drawing means the drawing forces which increase with increasing substrate thickness, and on the other, of ensuring the homogeneous overall heating of the sheets required for uniform drawing. However, commercially there is certainly a large demand for high-strength plastic sheets.
A contribution to solving this problem is provided by the process described in EP-A-0,207,047, which provides for the production of high-tenacity panels of high tensile strength by thermal compression of a plurality of biaxially oriented, coextruded plastic films. The panels obtained are in themselves homogeneous and have smooth, even surfaces.